Oven, furnace, or like structure



Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE LAN GELOT WILLIAMWILD, OF LONDON, ENGLAND, ASSIGNOR T0 WILD-BARFIELD ELEC- TRIG. FURNACESLIMITED, 01 LONDON, ENGLAND OVEN, FURNACE, OR LIKE STRUCTURE Applicationfiled April 18, 1930, Serial No. 445,262, and in Great Britain June 11,1929.

This invention relates to ovens, furnaces, or like heaters, adapted foruse in carrying out industrial processes, such as carbonizing,hardening, tempering, or other heat treatments which are carried out inhigh temperature furnaces.

In such furnaces the air is circulated to a certain extent byconvection. In order to increase the circulation of the air, propellorfans or fans having inclined blades have been utilized but have not beenentirely successful, due to the action of the pitched blade.

This invention has for its; salient object to provide air circulatingmeans for a furnace or oven of the character specified, so constructedand arranged as to supplement thenormal current of air produced byconvec tion and to increase the efficiency of operati on of the furnaceand cut down the time required for heat, treatment.

Further objects of the invention will appear from the followingspecification taken in connection with the drawings, which form a partof this application, and in which Fig. 1 is a sectional elevation of afurnace having air circulating means constructed in accordance withtheinvention; Fig. 2 is a transverse sectional elevation takiensubstantially on line-22 of Fig. 1; an c Fig. 3 is a view similar toFig. 1 but showing the fan at the top of the heating chamber instead ofat the bottom thereof.

The invention briefly described consists of a furnace comprising aheating chamber having suitable heating means therein and a paddle fanor a fan having plane blades disposed in the chamber and adapted tocause the air to circulate in a manner to supplement the normal currentproduced by convection. The blades are preferably arranged radially ofthe'axis of rotation of the fan.

Further 'details of the invention will ap pear from the followingdescription.

In the particular embodiment of the invention illustrated in thedrawings, there is shown an electric oven adapted particularly fortempering steel. It should be understood, however, that the invention isbroadly applicable to other types and forms of ovens and may be used inovens which are heated by gas, oil, or by solid fuel.

The oven 10 illustrated in the drawings is preferably made of sheet ironand is lagged with the usual lagging material '12 having poor heatconductivity. The furnace is charged through the top, the top beingnormally closed by a cover or lid 13, which is also lagged.

The furnace is provided with heaters 14 which are mounted in the cornersand extend vertically in the heating chamber of the fur is supported ina bracket 21 which extends below the bottom of the furnace.

The basket or work support 15 is preferably perforated in its side wall,as shown at 22, and in its bottom, as shown at 23, to permit thecirculation of the air through the sides and bottom of the basket.

By placing the fan beneath the work in the manner illustrated in Fig. 1,the normal current 3 of air' produced by convection through the heatersis supplemented, the fan operating to cause the air to be forcedlaterally. The air which is forced laterally by the fan is heated by theheaters and rises and the current of air carries the air inwardly anddownwardly to the work supported in the basket. The heated air passesdownwardly throughthe basket and is again acted on by the fan and thus acontinuous circulation is maintained. It has beendemonstrated that a fanof the paddle type above described materially increases the efliciencyof the furnace is cut down to a veryico nsiderable extent over the timerequired in the ordinary furnace or in the furnace having a propellortype fan for supplementing the circulation of the air therein.

The use of the paddle type of fan in a furnace or oven is not limited tothe particular mounting shown in Figs. 1 and 2 but has been found to bevery beneficial in a furnace structure such as that shown in Fig. 3. Itis not always practical to support the work to be treated in a basketwhich is spaced from the floor of the furnace and to mount the fanbetween the basket and the floor. For example, in high temperature ovensor furnaces, such as those used for carbonizing steel, it is impracticalto use metal supports for the work and the work is, therefore, usuallyplaced on the floor of the furnace. Furthermore, in large ovens orfurnaces where mechanical loading is employed, the loading mechanismordinarily delivers the work on the floor of the oven or furnace.

Under conditions such as those above described, the fan may be mountedin the manner shown in Fig. 3, in which the motor 20 is mounted on thecover or lid of the oven and the fan is disposed on the opposite side orinside of the cover. Instead of mounting the fan on the cover or abovethe floor of the furnace, it can be mounted on one of the verticalwalls. It has been found that the paddle type of fan, whether mounted inthe manner shown in Figs. 1 or 3, or on one of the vertical walls of thefurnace, materially increases the circulation of the air in the furnaceand results in a greatly increased efiiciency in the operation of thefurnace.

Although certain specific embodiments of the invention have beenparticularly shown and described, it will be understood that theinvention is capable of modification and that changes in theconstruction and in the arrangement of the various cooperating parts maybe made without departing from the spirit or scope of the invention, asexpressed in the following claims.

What I claim is:

1. A furnace comprising a heating chamber, heaters therein, a worksupport, and an air circulating fan disposed below said work 7 support,said fan having radial plane blades arranged to direct the air normal tothe walls of the furnace.

2. A furnace comprising a heating chamber, heaters therein, a worksupport, and an air circulating fan disposed below said work support,said fan having a vertical drive shaft and blades disposed radially ofsaid 3. A furnace of the character specified comprising a heatingchamber, heating means therein, and a paddle type fan in said chamberhaving blades vertically disposed relative to said chamber, fordirecting air normal to the walls of the furnace.

A furnace of the character specified compnslng a heating chamber,heating means ranged with its axis adjacent the center of the chamberand having fan blades extending radially of said axis and in planesintersecting in a line coinciding with said axis for directing the airnormal to the walls of the furnace.

LANCELOT WILLIAM WILD.

